Non-Patent Literature 1 discloses a photodiode in which an InGaAs/GaAsSb type II MQW structure is formed on an InP substrate as a group III-V compound semiconductor substrate to realize a cut-off wavelength of 2 μm or more.
Meanwhile, Non-Patent Literature 2 discloses an LED and a laser diode, in which an InGaAs/GaAsSb type II MQW structure is formed as an active layer on an InP substrate to realize an emission wavelength of 2.14 μm. In the type II MQW structure, GaAsSb has an Sb composition of 34 at. % to 40 at. %, that is, a strain-compensated structure is adopted, in which the Sb composition is smaller than the lattice match composition with InP. Note that “at. %” is simply referred to as “%” in the following description.
Further, single-phase GaAsSb layers having different Sb compositions are grown on an InP substrate without forming type II MQW, and PL wavelengths are measured. Then, an InP/GaAsSb type II MQW LED is examined.
Meanwhile, Patent Literature 1 discloses a semiconductor laser device having a GaInNAsSb quantum well structure. This GaInNAsSb quantum well structure is a single quantum well structure (i.e., the number of pairs is 1).